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Due to the new requirements on exhaust pollutant emissions, studies on new engine processes are currently being conducted. New combustion systems such as homogeneous charge compression ignition (HCCI) appear promising as they have the potential to achieve near zero particulate and NOx emissions. Nevertheless their main drawback is their unstable ignition start, inducing changes in the operating condition, because ignition is controlled only by the chemical kinetics, this has a limiting effect on the operating range of HCCI engines. Several strategies to improve the combustion initiation have been proposed, such as the adaptation of technologies (modification of the injection strategy or the bowl geometry), use of high EGR (Exhaust Gas Recirculation) rates or changes in the fuel formulation. This paper presents works done in the last two items.

Biofuels are an important means of progress to reduce greenhouse gases and local pollution and to diversify energy. For diesel engines, FAME (Fatty Acid Methyl Ester), coming from trans esterification of vegetable oils, have already shown their potential as fuel substitutes. Nevertheless, this trans esterification induces glycerol production as a co - product. At the same time, oxygenated compounds have been shown to have great potential for reducing diesel particulate emissions. So using glycerol as a basis to synthesize new oxygenated compounds, for diesel fuel formulation could be promising. This paper deals with the synthesis of oxygenated compounds coming from glycerol, such as acetals, ethers, or carbonates, and their evaluation as blending components in diesel fuel. The objective of this work is to evaluate their potential, in terms of pollutant emissions, with different engine technologies.

To reduce pollutant emissions coming from transportation, different solutions are available: technology improvement and fuel reformulation. Concerning the diesel fuels, the reformulation can be done through an evolution of the classical families of compounds as, for example, level of polyaromatic content or through a very promising way to reduce particulate emissions which is the introduction of oxygenated compounds. Many works have already been done and have confirmed the interest of these compounds. This paper is dedicated to a new approach of synthesis or selection of oxygenated compounds.

Air quality improvement, especially in urban areas, is one of the major concerns for the coming years. For this reason, car manufacturers, equipment manufacturers and refiners have explored development issues to comply with increasingly severe anti-pollution requirements. In such a context, the identification of the most promising improvement options is essential. A research program, carried out by IFP (Institut Français du Pétrole), and supported by the French Ministry of Industry, IFP, PSA-Peugeot-Citroën, Renault and RVI (Renault Véhicules Industriels), has been built to study this point. It is based on a three years program with different steps focused on new engine technologies which will be available in the next 20 years in order to answer to more and more severe pollutant and CO2 emission regulations. This program is divided into three main parts: the first one for Diesel car engines, the second for Diesel truck engines and the third for spark ignition engines.

Air quality improvement, especially in urban areas, is one of the major concerns for the coming years. For this reason, car manufacturers, equipment manufacturers and refiners have been exploring development avenues to comply with increasingly severe anti-pollution requirements. In such a context, the identification of the most promising improvement options is essential. A research program, carried out by IFP (Institut Français du Pétrole), and supported by FSH (Fonds de Soutien aux Hydrocarbures), IFP, PSA-Peugeot-Citroën, Renault and Renault VI (Véhicules Industriels), has been built to study this point. It is a four years programme with different steps which will focus on new engine technologies: some of them are going to be marketed very soon (gasoline direct injection car engine, and diesel common rail injection car and truck engines) to anticipate the Euro 3 (2000) and the Euro 4 (2005) emissions specifications. The original work reported here is part of this research.

The method proposed here, allows estimation of the fuel tendency to produce ORI. The procedure lasts 32 hours and is carried out on a dedicated CFR-engine. The ORI is evaluated by comparison of the KLSA (Knock Limited Spark Advance) level, between the beginning and the end of the procedure. In order to optimize the engine parameters, their influences on the ORI were investigated. Particularly, the impact of four of them fuel/air equivalence ratio, coolant temperature, spark advance, load) was precisely quantified, using an experimental design method. Combustion parameters were also followed during the tests. It was observed that the heat transfer modifications contribute greatly to the ORI. Thermal diffusivities measured on the piston-top indicated that deposits located on here are not the main source of ORI.

The use of biofuels in Europe is justified by the common agricultural policy decisions, by the need to improve environment protection and by the search of alternative fossil energy sources. In such a context, France decided to conduct a national experiment to demonstrate that a diesel fuel containing, up to 5%, rapeseed methyl ester (RME) could be handled as common diesel fuel by the distributors. Refiners (Elf, TOTAL), car and truck manufacturers (PSA, RENAULT SA RENAULT TRUCKS). French civil services (industry and agricultural departments ADEME) and an organization working on vegetable oils (ONIDOL) joined this program implemented and coordinated by IFP.

A CFR engine has been used to 1. Develop a test procedure to determine the influence of the fuel composition on Octane Requirement Increase (O.R.I.), 2. Examine the mechanism of this phenomenon. A short duration test procedure of 35 hours using a small quantity of fuel is proposed. Testing of several gasoline compositions has indicated reasonable repeatability and discriminating power between these gasolines. The mechanism proposed for O.R.I. combines two factors: First, thermal measurements have shown the insulating properties of the deposit layer, formed in the combustion chamber, which causes an increase in the temperature of the end-gas thus resulting in earlier self-ignition. Secondly, the occurrence of deposits on the intake valve produces an enhanced swirl. This factor and the increase of the temperature of the charge cause an acceleration of the flame speed. Computations show that the earlier combustion due to this acceleration contributes to the O.R.I.

A new criterion to assess diesel fuels has been developed at the Institut Français du Pétrole, in collaboration with PEUGEOT and RENAULT. It is a comparative method which makes it possible to assign a Particulate Number (PN) to a diesel fuel, calibrated, as for the cetane number, with two reference fuels specially formulated. One has a low emission level, the other one a very high level. Values PN=0 and PN=100 are respectively attributed to each of them. The first is made up of tetradecane, and the second of a highly aromatic mixture containing 55 % tetradecane, 40 % 1-methyl-naphthalene and 5 % phenanthrene. The PN value of a diesel fuel derives from measurements of particulate emissions of an engine successively fuelled with the three products (CPP) and from a simple analysis in laboratory of the nitrogen content (N) of the tested fuel.

The evolution of European requirements for the reduction of spark ignited engine emissions makes necessary a better understanding of the impact of gasoline formulation on regulated, photochemical and toxic pollutants. To this end, the effects of gasoline have been studied on a European four-cylinder engine, fitted with a three-way catalyst and operated at steady state conditions. A design for experiments with mixtures made it possible to study the effects of different classes of gasoline compounds, using n-pentane, isopentane, 1-pentene, cyclohexane, n-octane, isooctane, toluene, ethylbenzene, m- and p-xylenes and o-xylene introduced in an alkylate base stock. Aromatics, especially the more substituted ones, produce the greatest engine-out hydrocarbon emissions. They also increase the nitrogen oxide emissions. However, both unburned hydrocarbon and tailpipe nitrogen oxide emissions are decreased with aromatics.